Thread control mechanism for sewing machines



April 6, 1954 SCHWARTZ 2,674,214

THREAD CONTROL MECHANISM FOR SEWING MACHINES Filed July 8, 1950 IN V EN TOR. i0 5am/merz AU 35AM and operator.

Patented Apr. 6, 1954 THREAD CONTROL MECHANISM FOR SEWING MACHINES Leo Schwartz, New York, N. Y.

Application July 8, 1950, Serial No. 172,657

2 Claims. (Cl. nfl-219) The present invention is directed to a control mechanism for sewing machines, more particularly to a device which operates so that when a thread breaks, the machine is automatically stopped.

In the needles industries, high speed sewing machines are used for quantity production. Such machines run at speeds of 3G00 or 4000 R. P. M. or even higher. Therefore, the production of garments is at a high rate since the fabric runs through the machine at a high speed. However, when the thread breaks or a bobbin becomes exhausted, the machine continues to feed the fabric without completing the sewing. In a few seconds a considerable amount of fabric may thus pass through the machine before the machine can be stopped manually. This necessitated removing the fabric from the machine and pulling it back to `a position where the stitching had ended. Such procedure wasted considerable time and it interfered with the productivity of the machine To overcome these disadvantages, it has been proposed to provide automatic means for stopping a sewing machine when the thread breaks. arrangements which were actuated by the break-n ing of a thread to cause mechanical movements to take place, disconnecting the machine from the driving means, or stopping a motor or the like. Such expedients were not fully effective for the desired purpose since they did not operate inn stantaneously but required several seconds for operation so that it did not stop the machine immediately upon the breaking of va thread.

The present invention is intended and adapted to overcome the diliculties and disadvantages inherent in prior devices of the type described, it being among the objects of the present invention to provide a control device for stopping a sewing machine which is set into action by the breaking of a thread. y

It is also among the objects of the present invention to provide a device which is highly sensitive and which operates instantaneously upon the breaking of a thread to electrically stop the operation of the machine.

It is further among the objects of the present invention to provide a device of the character described, which is simple in construction, positive in operation and which may bev subjected to use on high speed machines for long periods of time without deterioration.

In practicing the present invention there is providedan element which is suitably mounted and usually on the arm or head of a sewing machine.

It includes a plunger mounted for longitudinal movement and having an eye at one end thereot` through which a thread is passed from a spool to the needle of the machine. A coil spring surrounds a portion of the plunger and is so arranged that it tends to retract the plunger against. the

Among such devices were mechanical tension of the threads. At the other end of the plunger is a contact which is adapted to be moved into operative relation with a xed contact whereby an electrical circuit is formed. This occurs upon the breaking of a thread whereby the action of the spring causes closing of said contacts or switch.

There is further provided a solenoid having an armature, the solenoid being in the circuit with the aforesaid switch. A latch arrangement is provided to hold a catch in a certain position, allowing operation of the machine. Upon actuation of the solenoid, the catch is released, causing a shaft to be oscillated and a clutch to be disengaged. By such an arrangement, within a fraction of a second of the breaking of a thread, the machine can be stopped.

In the accompanying drawing constituting a part hereof and in which like reference characters indicate like parts,

Fig. 1 is a perspective view of the head and arm of a sewing machine, showing the switching arrangement in position relative to the thread and needle;

Fig. 2 is a longitudinal cross-sectional yview taken through the switching device;

Fig. 3 is a top plan view of the stop mechanism, some parts being removed for clearness;

Fig. 4 is a view similar to Fig. 3, showing only the left-hand portion with the elements in a different position, and Fig'. 5 is a transverse cross-sectional view taken along the line 5 -5 of Fig. 3.

There is provided the usual arm I and head 2 of a sewing machine containing the ordinary sewing instrumentalities and having in this case a pair of needles 3. The device is applicable to a single needle machine as well as a multiple needle machine. A pair of thread tensions 4 carry threads 5 through a suitable eye 5 and then in 4operatiwe relation with element S which is atand I2 therein, carrying plungers I3 and I4, re-

spectively A pair of spaced bearings l5 and I5 is provided for plunger it and a similar pair of spaced bearings ifi and Iii are provided for plunger Id. Blocks I? and i3 are xed on plungers i3 and It, respectively, and coil springs I9 and 20 surround said plungers, bearing against the blocks at one end and bearings I5' and I S at the other end.

The plungers are provided with eyes 2l and 22, respectively, through which threads 5 are adapted to pass. At the opposite end of casing 6 are insulating elements 23 fixed to said casing and having a conducting plate 24 on the outer end thereof. A terminal 25 is secured to plate 2A to accommodate a wire 26. Plungers I3 and I 4 3 have at their left hand ends heads 21 and 28, respectively, carrying contact members 21 and 28'. Corresponding xed contact members 29 and 30', respectively; are provided on'theinside of plate 24 adjacent to heads 21 and 28.

Plate 3l is secured to the end of casing G adjacent to eyes 2| and 22. Arms 32,and 33 extend at approximately right angles to plate 3`l andi have openings 34 and 35 in the ends thereof. Threads 5 are adapted to pass through openingsI 35, then through eyes 2i and 22, throughbpenings 34 and.

then to the needles, as shown in Fig. 1.

.The actuating mechanism for the stop mechanism consists of a casing 36 open on one side and adapted to beclosedby cover 31 and set. screws 38.. Anoperating handle 39 is secured toone end of. shaft, passing-through casing 36. The other end of handle 39 is suitably securedto a clutch or otherelement whereby onoscillation of said shaft, theclutch is disengaged, or any other usual element is moved to stop operation of. the machine.

Block 4I is xed. on. shaft. 40 and. coil, spring 42 issecured to .the block and. the casing atits ends so-as tonormally biasshaft inthe.Y direction of. the-arrow. Asolenoid 43 has armature. mounted. thereinv for longitudinal movement. Block .45fis secured thereto andretains coil spring surrounding it and normally biasing the armature in the direction of the arrow.. Pin 41 extending into casing 3B is in contact with the end of armaturellll and may beused manually-for. retracting saidL armature: by pressing on. the head of said pin.

An .arm48fis xed-onshaftlt. Pivoted at 49 to.-armatur.e 44 is latchmountedonpin 5i` for oscillation; Latch. lhas av recess 52 thereinfor the reception of catch 53 mounted on arm 48. Stop 54. limits theoscilla-tion of shaftA-by contacting with arm 48,.

Said` arm carries contact member 55 adapted to close a circuitwithacomplementary contact member on the endof resilient blade. 56 which is secured` to insulating block.- 51, the latter being mounted in casing 3S. Blade-58. on the opposite side cfmember-STI is electrically connected therewith and has a wire 59 attached to one of the terminals of: solenoid 43. Wire- 26. isattachedto terminalA 60. which is the` otherv terminal. of the solenoid.

In the.. operation of. theY device, the. elements are inthe-.position shown inFigs. 1 and,3 andthe plungers are intheposition of plunger I3.inFig. 2.- The solenoid circuit isbroken., Whenathread breaks as. shown in, Fig. 2. by. ther position. of plunger i4, the tensionv having been. released and spring 2l)v causing contacts. 28 and. 30 to. close, current flows through wireZB-and the other elements ofthe circuitincluding solenoid 43.. This retracts. arrnatureJM,v oscillating latchv to the right. as shown in Fig, 4, releasing arm 481 and catch. 53.. This allows spring., 42 to twistshaft 4D.A in. the. direction of the arrow until arm 48 contactsstop 54. The twistingv action causesoperation of a clutch or other element to stopthe machine.

In order to startthe machine after the needle is rethreaded, handle 39 is pressed seas to twist shaft 40 in a direction opposite to thearrow, thus allowing arm. 48 and. catch. 53 to move intolocking position, as shown in Fig.. 3. If during. the operation of the machinethe operator desires-to stop it, he merely presses pin. 41, causing armature 44.130. beA retracted, arm- 48` toV move upwardly, breaking: a circuitrof contacts --56.

Although the invention has been described setting forth a single specific embodiment thereof, various changesI in the detailsi of construction may bev made within thel principles herein set forth. For instance, casing 6 need not be of rectangular form but may be of any suitable shape. It may. be mounted on the head of the machine or adjacent to the needles and fixed to the bed or other stationary part. The plungers and'associated elements may be of different form and they need not be parallel to each other.

These and other changes may be made within thefspirit-of the invention, which is to be broadly construed and not tof. be limited except by the character of.` the claims appendedhereto..

I claim:

1. In a thread control. mechanism for a sewing machine comprising a hollow casing adapted to be attached to said machine, at least one plunger mountedA in said casing for longitudinal movement therein and. extending out of one end thereof, an electrical contact on the pcrtionof said plunger within said casing, an eye on the extending endof said plunger and through which a. tensioned thread is adapted toA pass, a fixed electrical contact in said casing in cooperative relation with said plunger contact,y resilient means. in said casing and surrounding` said plunger biasing said plunger towardssaidfixed contact against the tensionof said. thread,` the improvement which includes ar solenoid having an electricalconnection to said.,xed.contact,.an armature longitudinally movablein said solenoid, a latch pivoted on said. armature, a. shaft adjacent to saidarmatureandhaving an armsecured thereto, said arm carrying a catch, said. latch having a recess cooperating with said.cat'ch'said catch adapted to enter said latch.

2.. In a thread control mechanism. for asewing, machine comprisinga hollow casing adapted to be attached to said' machine, at least. one plunger mountedin said casing. for longitudinal movement therein and extending out of one end thereof, an electrical contact on4 the portion of said plunger within said casing,..an eye on the extendingr end ofA said. plunger and through which a tensioned thread is adapted to, pass,v a fixed electrical contact in said casing in cooperative relation with said plunger contact, resilient means in said casing and surrounding said plunger biasing said plunger towards said xed contact against the tension. of said4 thread, the improvement which. includes a. solenoid. having an. electrical connection to said 'xed contact, an armature longitudinally movable in said solenoid, a latch pivoted on said armature, av shaftl adjacent to said armature and having an arm secured thereto, said arm carryinga catch, saidlatch having a recess cooperating with said catch, said catch adapted to enter saidlatch, aspringsur.- rounding said shafttencling to. twist said. shaft to maintain said. latch.- and. catch.. out of.V engagement..

References Cited in the: leof this patent.

UNITED STATES PATENTS Number` Name Date 1,042,602v Robertszet al. Oct; 29, 1912 2,140,09I1l Newell Dec. 13,1938 2,241,682 Wachsman- May 13, 1941A 2,287,203 Vossen .June 23, 1942 2,483,541 Hoag Oct. 4, 1949 2,490,936.v 'VossenV Dec.- 13, 1949 2,491,970y Grant Dec; 20, 1949 

